Belt drive



March 5, 1929. l A, R, CUR-ns 1,704,532

BELT DRIVE Filed April 23, 1923 @mmm/ I ings.

Patented Mar. 5, 1929.

Aii'riiui-t R. CURTIS,l or CLEVELAND, oHio.

' BELT DRIVE.

Application filed April 23, 1923. SerialNo. 633,972.

This inventionrelates to V'belt drives, ,and

has for its object to provide means for tightening the belt andreleasing the tension thereof and for disengaging the belt from one oli"its pulleys when `its tension is released.

A further object is to provide a belt disengaging means which acts toexpandV the portion of the belt passing' around the pulley out ofcontact with the pulley when the tension is released and to releasablyhold the belt out of contact with the pulley in such position that thebelt will move intov engagement with the pulley when the belt is againtightened.

A further object is to provide abelt drive in which the belt and pulleysover which the belt passes are horizontally disposed and the drivingconnection between the pulleys is controlled by the actuation of a belttightener.

A further object is 4to provide abelt drive in which the belt while inoperation is main-V tion in which Fig.. l is a top plan view of a beltdrive embodying the present invention;

. Figs. 2 and 3 are end and side elevations respectively of the driving.mechanism shown in F ig. l. While the present invention is Vof quitegeneral application, the belt drive heref in, shown yis one designedparticularly for operating a washing machine and is interpesedbetween anelectric motor l and automatic gearing for driving the washer cylin-`der alternately in opposite directions con tained within the gearhousing 2.' The motor 1 is supported upon the framework of the machinewith the shaft 3 thereof disposed vertically andthe motor shaft 3 has agrooved driving pulley l vfixed to the iippe'i` end there-v of. Themechanism within the gear housing 2 is driven through a'verticallyrrdisposed l belt.

shaft 5 which extends downwardly through the` lower end of the housingand has" a grooved pulley GliXed to the lowerend tliereof in horizontalalignment with the grooved pulley 4.at the upper end of the inotorshaft.A belt 7 which is preferably round in crosssecvtion passes around thehorizontally aligned groovedldriving and driven pulleys l and 6. Asuitable belt tightener is provided for upon the ldriving `belt 7 toprevent slipping of the belt during the operation of the machine.

arni 9 ofl a bell crank actuating leveiylthe other arm lUof which formsthe handlevbyd I means of which Vthe lever is shifted to move the roller8 into and out of engagement with the belt. The bell-crankactuatinglever is pivoted to the underside of the gearhousing '2 and theVoutwardly extending handle 10 thereof has upon its .upperside an acuatepivotal axis of tlielever as a center.` rlhe upper inclined surface ofthe bearing cam l1 is engaged bya plunger` l2 which is dis-V posedverticallyand is slidable in a bracket 13 attached to the side of thegea'rhousing and The belt* tightener comprises a- Vgrooved horizontallykdisposed roller 8 which engages the belt 7 between the pulleys fl and 6and is carried upon the outer end ofthe v price. l

maintaining the proper amount of tension vr bearing cam `11wvhich` iscurved about the sov is pressed downwardly into engagementwith 1 o thecam ll by a coil spring 14v bearing against the upper end' thereof. Thespring pressed plunger l2 acting upon the inclined vsurface of the Cainll acts to shift the lever in a direc-` tion to move the roller 8 intoengagement with the belt and to'eXert a pressure upon the roller 8 toapply a predetermined tensionl to the' belt.V Movement Aof the roller8'Vaway from the belt, however, iis resisted not only by the force'of'the spring lbutal'so by the cani 1l when pressing outwardly upon thelower end of the plunger causing lthe plunger frictional drag of theplunger' l2 in tliecasing in which 1t slides, the inclined surface ofthe' to bindin its casing so that a force greater f than thatrequiredto, overcomelthe tension. ofthe spring is required yto niove'the rollervWhen the cam llis pressed in a direc-f` tion to tighten thev belt,pressure at the rub- 8 in a direction to release the tension of the bingpoint a of the plunger 12 on the cam is simply that of spring14` and thepressure at the point indicated at b, in Fig. 3, between the plunger andits casing, is that due to the vwedging action of the plunger againstthe j inclined face of the cam minus thefrictional drag fat a, whichlatter makesV the pressure frictional resistaiiceto the 'moven'ient ofthe slack due to stretching of the belt.

lfrictional resistance to outward movement of the roller 8, however,serves to hold the roller vgreater force is required' to move plunger'in its casing so 'that aV considerably the tightener outwardly thanV.that required to overcomethe "tension of the spring. Hence,adifferential friction device is provided which offers almost noresistance to the tightening` movement but which offers a substantialre# sistance to reverse movement; Then the roller8 yis in lengagementwith the belt the ,plunger 12 is bearing upon the inclined porn tion ofthe cam 11 so that the roller 8 is constantly urged in a direction toltighten the belt and will move inwardly to take up any againstvibratory movements vduring the operation of the belt.

It will be noted that the inclined face of the cam 11 which is engagedby the plunger 12 y has a varying inclination so that the pressureexerted'bytlie spring 14 upon the tightener varies in differentpositions of the tightener. In Fig. Sfofthe drawing, the tiglitener `isVshown in a position in which it has been moved inwardly toits fullextent of movement' in normal operation and in this position the plunger12 is engaging at substan-v tioally the lowermost point of the inclinedfportion of the cam. It will also be observed that the curvature of thecam and the iii-V clination thereof gradually decreases toward theuppermost part of the incline. The effect of the cam is to equalize thepressure transc f mitted from the 'spring to the tiglitener. The

inclination of the por-tion of the cam, engaged by the plunger,gradually increasesl as the retainer 'moves inwardly so that theV'Compression spring 14, while under less tension,

will still exert substantially the same pressure against the beltbyreason of the fact that the plunger is acting against the steeperportion of the surface of the cani. Y

lVhfile the frictional drag resisting outward i movementoffthe tighteneris vsufficient to prevent lvi'bratory. movements of thetighteiier,litris not suflicient to prevent manual f operation thereofor outward movement dueto the shortening of the belt due to shrinkage.

An arcuate guard 15 which is channelshaped in cross-section is arrangedaround the periphery of the pulley 6 closely adjacent the belt 7 Vwithits flanges projecting inwardly over the'upper and lower flanged edgesof the pulley. The arcuate guide 15 serves to maintain the belt 7 inengagement at alltimes with Ythe driven pulley 6 and to shift the slackof the beltwhen the tension thereof is released toward the drivingpulley 4. the driving pulley 4 on the side of the shaft 3 towardthe'pu-lley 6 isa bracket 16 fixed Vto the upper endof the motor 1 andprovided with belt `engaging edge flanges 17 and 18 which are closelyadjacent the belt 7 on opposite sides of the pulley 4. The flanges 17and 18 are V-shapedvin cross-section and converge slightly toward theirouteiends, Vhenever the tension of the belt 7 is released by moving theroller 8 out ofiengagemeiit therewith, the slack of the belt 7 isshifted towardthe pulley 4 bythe arcuate guard 15 and the'portion "ofVthe belt passing around the driving pulley'4 is thrown outwardly bycentrifugal force and by its natural elastic expansion into engage-4ment with the V-shaped flanges 17 and-18 which hold the belt entirelyout of contact vwith the driving pulley 4. The Vnshaped flanges 17andj18 are arranged with the bottoms of the Vsin the central plane ofthe ad-V jacent pulley so that when the belt expands outwardly intoengagement with the flanges, it is guided toward the bottoms of theVsand held in the plane of the grooves of the pulley so that it cannot'rubagainst either flangeof the pulley, the outward pressure due to theUnderneath Y Aelasticity of the belt serving to firmly hold the beltin'engagement with the flanges and out of f Contact with the pulley.Vheii the roller 8 is again shifted to tighten the belt 7 the'beltfisinstantlyv drawn out of engagement'with the flanges 17 and 18 and intoengagementwith the peripheral groove of the driving pulley 4. It willthus be seeny that the arcuate guide 15, together with the belt'engagingflanges 17 and 18 provide means for automatically rew'henever'thetension of the belt is released;

and that the belt holding flanges 17 and 18 are so disposed that uponreengagement of the belt tightener with the belt, the belt is drawn intoengagement with the driving pulley.-r

Vhen a new belt is applied'to the pulleys, its length will be justsufficient to provide the slack necessary to permit the belt to freeitself` from the pulleys when the'tightener is re-' leased, and as thebelt stretches in operation, the additional slack will be automaticallytaken up by the tightener which has a range of movement sufficient totakeup whatever additional vslack is' formed by'elongation of the belt.Y Y

Having 'n 1.'A belt drive compiisinga drive pulley,

described my invention, I claim-Lf imY lleasing the belt from thedrivingpulley 4,

a driven pulley, a beltpassing around said pulleys, a manually operablebelt tightener and adjustable tol 'engageable with the belt tighten thebelt or release the tension thereof.

o 1 n an arcuate guide member outside tne belt and closely adjacent theportion thereof engaging` the circumference or" the driven pulley, 'andconverging belt engaging members on the outer sides of opposite runsofthe belt and closely adjacent the drive pulley, said converging beltengaging members being norially out of contact With the belt but adaptedto be engaged by the belt when the tension thereof is released todispose the slack of the belt about tho driving pulley whereby the beltis disengaged from the driving pulley.

2. A belt drive comprising a grooved driving pulley, a grooved drivenpulley, a belt which is round in cross-section passing around saidpulleys, a manually operable belt tightener adjustable to tighten thebelt or to release the tension thereof, an arcuate guard outside theportion of the belt passing around the driven pulley and closelyadjacent thereto, and a pair of belt engaging members outside theopposite runs of the belt closely adjacent the driven pulley, said beltengaging members having substantially l! -shaped belt reccivinfYo'rtions in which the belt eno'affes when the tension thereof is`released and which coact with the belt to hold the same out of contactWith the driving' pulley. Y

8. A belt drive comprising a driving pulley, a driven pulley, a slackbelt passing around both said pulleys, means for tightening-andreleasing the belt and belt holding members trough-shaped incross-section positioned on opposite sides of one of the pulleys withthe mid-center lines of the troughs lying in the mid-plane of thepulley.

4. A belt drive comprising a driving pulley, a driven pulley, a beltpassing around said pulleys, a tensioning device for said belt includinga cam, a spring pressed actuating member co-acting with the sloping faceof `said cam to actuate the tensioning device in a directiontotensionthe belt, said vtension tending to vary With change in theposition of the tensioningdevice, said cam having vari ations in itsslope to maintain a substantially constant tension in the beltregardless of the position of the tensioning device.

5. A belt drive comprising a driving pulley, a driven pulley, a beltpassing around said pulleys, a tensioning device for said belt having apulley adapted to engage the same, said device having a cam, a springpressed member co-acting with the sloping face of the cam to applypressure to the pulley to tension the belt, the slope of said cam beingso varied on different portions' thereof as to give predeterminedpressures on the pulley for successive positions of the tensioningdevice.

6. A belt drive comprisinga driving pulley, a driven pulley, a beltpassing around rvthe roll-erl to shift the same to and from tightsaid.pulleys, a` swinging tensioning device forsaid belt carrying'a pulleyadapted to engage'the same, said device having an' arcute cam, and aspring pressed member coacting Withthe sloping face ofsaid cam to apply,pressure to the pulley to tension the belt, the slope of said cam beingso varied'as to give predetermined pressures on said pulley forsuccessive positions of the tensioning device.

7. A belt drive comprising a driving pulley, a driven pulley, a` beltpassing around said pulleys,.a belt tightener engaging said belt, aspring acting inwardly upon said tightener to exert pressure upon thebclt to tighten the same, and frictional means acting on the tightenerfor exerting a drag thereon y upon outward movement thereof wherebyvibratory movements of the tightener during the operation of the beltare prevented.

8. A belt drive comprising a drive pulley, f a driven pulley, a beltpassing around said pulleys, atightening roller engageable 'With one runof the belt, a lever connected vvithv ening position, a spring actingupon saidv lever to move the same in a direction to tighten the belt,and frictional means interposed b tiveensaid lever and spring for eX-erting a frictional drag upon the movement of the lever in the oppositedirection whereby vibrator-y, movements of the tightening roller areprevented. v

9. A belt drive comprising a driving pulley, a driven pulley, a beltpassing around said pulleys, and a belt tightener comprising y levercarrying a roller engageable With the belt, said lever having an arcuateinclined bearing surface, and a spring pressed plunger engaging saidarcuate bearing surface and acting to shift the lever in a directionpress the roller against the belt.

lO. A belt drive comprising a driving pulley, a drivn pulley, albeltpassing around said pulleys, a pressure operated means for tensioningthe belt having fric'tional resisti ance thereinopposing movementthereof, autoniatic means to cause the frictional resistance to movementin a direction to release the belt to be greaterl than the resistancetomovement in a direction to tension the saine, and pressure compensatingmeans to maintain a substantially constant tension in saidl belt.

n .plying means and acting onthe inclined survface to shift thetightener toward the belt.

12. 'A belt drive comprising a driving pulley, la driyen pulley, a loeltpassing around said pulleys, ya belt tightener engaging said belt, saidtightener comprising a movably mounted member carrying a roller engagingthebelt, said' vmember having an inclined bearing surface, 'which hasportions of different inclinations, a pressure applying means, a plungerassociated with the presysure applying` means and acting *ontlieAinclined surface to shift the tightener towards the belt. v

In testimony whereof, I hereunto aifiX my signature.

ARTHUR R.. CURTIS.

